using UnityEngine;
using System.Collections;
using System.IO;
 

public class Wav  
{

    // convert two bytes to one float in the range -1 to 1
    static float bytesToFloat(byte firstByte, byte secondByte) {
        // convert two bytes to one short (little endian)
        short s = (short)((secondByte << 8) | firstByte);
        // convert to range from -1 to (just below) 1
        return s / 32768.0F;
    }

    static int bytesToInt(byte[] bytes,int offset=0){
        int value=0;
        for(int i=0;i<4;i++){
            value |= ((int)bytes[offset+i])<<(i*8);
        }
        return value;
    }

    private static byte[] GetBytes(string filename){
        return File.ReadAllBytes(filename);
    }
    // properties
    public float[] LeftChannel{get; internal set;}
    public float[] RightChannel{get; internal set;}
    public int ChannelCount {get;internal set;}
    public int SampleCount {get;internal set;}
    public int Frequency {get;internal set;}
    
    // Returns left and right double arrays. 'right' will be null if sound is mono.
    public Wav(string filename):
        this(GetBytes(filename)) {}

    public Wav(byte[] wav){
        
        // Determine if mono or stereo
        ChannelCount = wav[22];     // Forget byte 23 as 99.999% of WAVs are 1 or 2 channels

        // Get the frequency
        Frequency = bytesToInt(wav,24);
        
        // Get past all the other sub chunks to get to the data subchunk:
        int pos = 12;   // First Subchunk ID from 12 to 16
        
        // Keep iterating until we find the data chunk (i.e. 64 61 74 61 ...... (i.e. 100 97 116 97 in decimal))
        while(!(wav[pos]==100 && wav[pos+1]==97 && wav[pos+2]==116 && wav[pos+3]==97)) {
            pos += 4;
            int chunkSize = wav[pos] + wav[pos + 1] * 256 + wav[pos + 2] * 65536 + wav[pos + 3] * 16777216;
            pos += 4 + chunkSize;
        }
        pos += 8;
        
        // Pos is now positioned to start of actual sound data.
        SampleCount = (wav.Length - pos)/2;     // 2 bytes per sample (16 bit sound mono)
        if (ChannelCount == 2) SampleCount /= 2;        // 4 bytes per sample (16 bit stereo)
        
        // Allocate memory (right will be null if only mono sound)
        LeftChannel = new float[SampleCount];
        if (ChannelCount == 2) RightChannel = new float[SampleCount];
        else RightChannel = null;
        
        // Write to double array/s:
        int i=0;
        while (pos < wav.Length) {
            LeftChannel[i] = bytesToFloat(wav[pos], wav[pos + 1]);
            pos += 2;
            if (ChannelCount == 2) {
                RightChannel[i] = bytesToFloat(wav[pos], wav[pos + 1]);
                pos += 2;
            }
            i++;
        }
    }

    public override string ToString ()
    {
        return string.Format ("[WAV: LeftChannel={0}, RightChannel={1}, ChannelCount={2}, SampleCount={3}, Frequency={4}]", LeftChannel, RightChannel, ChannelCount, SampleCount, Frequency);
    }
}

